1. Field of the Invention
The present invention relates to a controlling device connected to an information reproduction apparatus via an IEEE 1394 serial bus for remote control of the information reproduction apparatus, and to a home network in which the controlling device and the information reproduction apparatus are connected via the IEEE1394 serial bus.
2. Description of the Related Art
Controlling devices are known that control an information reproduction apparatus (hereinafter referred to as a reproducer) such as, for example, a digital VTR (Video Tape Recorder) via the IEEE1394 serial bus (abbreviated as the bus, hereinafter). In such a conventional device, there are cases where a control command cannot be sent to the reproducer until the status of the reproducer is checked. That is because, when a rewind or fast-forward key is pressed, the controlling device should send to the reproducer a rewind or fast-forward command if the reproducer is at a stop, and a rewind playback or fast-forward playback command if the apparatus is during playback operation.
Referring now to FIG. 5, a description will be made as to the steps performed in the case where a playback key is pressed and then the rewind key is pressed on the controlling device side. When the playback key is pressed (S101), the controlling device sends to the reproducer an Audio Video/Control (AV/C) command frame, which is a Function Control Protocol (FCP) packet frame to be sent from controller side to target side, containing a playback command (S102). When receiving the command frame and normally accepting the playback command, the reproducer creates an AV/C response frame, which is an FCP packet frame to be sent from target side to controller side, to the playback command (S103) and then sends the response frame to the controlling device (S104). Upon receipt of the response frame, the controlling device sends an AV/C command frame containing a status inquiry command to the reproducer (S105). When normally accepting the status inquiry command, the reproducer creates an AV/C response frame to the status inquiry command (S106), and then sends the response frame to the controlling device (S107). After checking the response frame to verify that the reproducer is during playback operation, the controlling device sets a reproduction flag bit (see the item denoted by reference number 18 in FIG. 1) in a RAM “on” (S108). When the rewind key is pressed in this state (S109), the controlling device determines what kind of command should be sent to the reproducer based on the pressed key and the reproduction flag bit in the RAM (S110) and sends a command frame containing a rewind playback command to the reproducer (S111).
However, in the above described controlling device, which, in response to the depression of the rewind or fast-forward key following the depression of the playback key, checks that the reproducer is during playback operation before the determination of the control command to be sent, it is necessary to wait for the response to the inquiry as to whether the reproducer is during playback operation or not. As a result, the controlling device cannot quickly send the rewind playback or fast-forward playback command to the reproducer. In order to prevent the above delay when the playback key and the rewind key are pressed in succession, if, as shown in FIG. 6, the steps corresponding to S105 to S108 in FIG. 5 are omitted such that the controlling device determines the control command to be sent depending only on the most recently pressed key without checking whether or not the reproducer is during playback operation (S126), not the rewind playback command but a rewind command may be sent by mistake (S127).